A push cart having an expansion unit for expanding load-carrying surface includes a movable cart frame, a load-carrying plate, an expansion unit and a coupling mechanism. The load-carrying plate is installed on the cart frame. The expansion unit includes at least one expansion plate. The coupling mechanism includes at least one coupling unit for detachably coupling the expansion plate to one side of the load-carrying plate. The coupling unit includes a female component disposed in one of the load-carrying plate and the expansion plate and a male component disposed on the other one of the load-carrying plate and the expansion plate for mating engagement with the female component.